Method of inhibiting the germination of grass seeds



- Patented July 21, 1964 3,141,758 METHOD OF INHHBITING THE GERMINATIONF GRASS SEEDS Philip C. Hamm, Webster Groves, and Angelo John Speziale,Creve Coeur, Mm, assignors to Monsanto Company, a corporation ofDelaware No Drawing. Filed July 7, 1961, Ser. No. 122,427 6 Claims. (Cl.71--2.6)

This invention relates to new herbicidal compositions and methods fortheir use. Although the compositions can be used both in contactapplications and in preemergence procedures, the latter is moresignificant, since it enables a selective activity on grasses withoutinjuring the broad-leaf crop plants.

Many chemical compounds are known to be deleterious to the growth ofvegetation and to have herbicidal effects under certain specificconditions; some of these are known to be quite effective at low levelsof application. It is, however, a more difficult problem to provideuseful herbicides for selective activity on undesirable plants, butwhich are harmless to other vegetation. Compounds of this type areknown, being primarily useful in eliminating broad-leaf plants fromgrasses or grass-like cereal corps. This herbicidal activity isfrequently related to the leaf area exposed to the herbicide, the plantswith larger leaf areas being more susceptible to the contact herbicides.

In copending applications of earlier date the present applicants haveshown that certain alpha-halo-acetamides are excellent herbicides,particularly with respect to grasses. It has also been shown that manynear homologues are inactive and that the active compounds have criticalmolecular configurations which are necessary to produce the desiredherbicidal effect. It has been demonstrated that the mono-halo acetylradical is an essential radical, but not all compounds containing theradical are useful herbicides. For example, the mono-halo-acetamide isinactive, but can be converted to an active herbicidal compound byproperly substituting on the nitrogen atom. The number and kind ofsubstituents to produce active herbicides have no relgular pattern andthe classes of compounds which have high degrees of activity areunpredictible and no theory of the herbicidal mechanism has yet beensuggested. A few general observations have been made with respect to thelimitations in structure and these provide the basis for separatepatenability in several copending applications.

The primary purpose of this invention is to provide a new and usefulclass of herbicides having both contact and pro-emergence herbicidalproperties. A further purpose of the invention is to provide selectiveherbicides capable of destroying grasses in the presence of broadleafcrop plants. A still further purpose of the invention is to provide newchemical compounds having unusual utilities as are hereinafter describedmore fully.

Although previous study of the alpha-halo-acetamide herbicides hasindicated that only one cyclic radical can be substituted on the amidenitrogen and this must be no more than one carbon atom removed from thenitrogen, it has now been shown that the presence of an oxygen or asulfur atom (chalkogens) adjacent the cyclic radical and between thesaid cyclic radical and the amide nitrogen atom induces a substantialmodification of the ever if there are two radicals having chalkogenatoms adjacent rings then the chalkogen atoms must be separated from theamide nitrogen by at least three atoms. The new compounds useful in thepractice of the novel procedures have the structural formula whereinZ--Z is a hydrocarbon ring of the group consisting of benzene,cycloalkene having from four to eight carbon atoms and cycloalkane offrom four to eight carbon atoms; wherein X is a chalkogen of the groupconsisting of oxygen and sulfur; wherein R is a radical of the groupconsisting of hydrogen, aliphatic hydrocarbon radicals of up to sixcarbon atoms, the oxa-aliphatic hydrocarbon radicals having up to sixcarbons atoms, and the said hydrocarbon and oxahydrocarbon radicalscontaining chlorine substituents; wherein Y is an alkyl radical of up tofour carbon atoms; wherein W is selected from the group consisting ofchlorine and bromine; wherein n is an integer from one to four; whereinm is an integer from zero to three; wherein t is an integer from zero tothree; wherein q is an integer from one to two; wherein p is an integerfrom zero to three; wherein r is an integer from one to four; andwherein when q is two and p is zero it must be at least three.

The new compounds are prepared by contacting a haloacetyl chloride, suchas bromoacetyl chloride or chloroacetyl chloride, with an amine havingone or two of the desired substituents in the presence of an alkalimetal hydroxide. The reagents are gradually combined so as to provide acontrolled reaction rate, using a cooling medium if required. Furtherdetails of the preparation will be hereinafter described in specificexamples.

Several distinct types of the new class of compounds are recognizable,for example Clm wherein Y, n, m, s, t and p are as above defined and R'is an aliphatic divalent hydrocarbon radical of up to six carbon atoms.

Representative compounds include:

Another type may be represented by the structure Clm wherein the severalsymbols are as above defined. This type includes the compounds:

Alpha-chloro-N-phenylthiopropyl acetamideAlpha-chloro-N-ethyl-N-phenylthioethoxyethyl acetamideAlpha-chloro-N-phenylthiomethyl acetamideAlpha-chloro-N-allyl-N-phenylthiopropyl acetamideAlpha-chloro-N-n-propyl-N-phenylthiomethyl acetamide Another group ofcompounds embraced by the generic formula are those of the structure thesymbols of which are as above identified.

Representative compounds include:

Alpha-chloro-N-4-chlorocyclohexyloxypropyl acetamideAlpha-chloro-N-allyl-N-cyclohexyloxyethyl acetamideAlpha-chloro-N-cyclohexyloxypropyl acetamideAlpha-chloro-N-4-isopropylcyclohexyloxyethyl acetamideAlpha-chloro-N-ethyl-N-cyclohexyloxymethyl acetamide A still furthertype of compound in the generic scope is evident the symbols of whichare above identified.

Representative compounds include:

Alpha-chloro-N-cyclohexylthiopropyl acetamideAlpha-chloro-N-allyl-N-cyclohexylthiomethyl acetamideAlpha-chloro-N-ethyl-N-cyclohexylthioethyl acetamideAlpha-chloro-N-4-methylcyclohexylthiopropyl acetamideAlpha-chloro-N-cyclohexylthioethyl acetamide The above four subgenericclasses include many of the more readily available compounds but they donot include all of the useful compounds embraced by the generic claim.Compounds with valuable properties which are excluded from the abovesubgeneric formula are:

4 Further details of the preparation of the compounds are set forth inthe following specific examples:

Example I A suitable reaction flask is charged with cc. of chloroformand 15.9 g. of 3-phenoxypropyl 2-methoxyethyl amine and 17.5 g. of 20%sodium hydroxide. The reaction vessel is then cooled to -10 to -20 C.and over a half hour period 9.7 g. of chloroacetyl chloride is addedthereto. After standing for three hours the organic liquid is separatedfrom the aqueous liquid and the chloroform evaporated from the organiclayer. The resulting product is distilled in a vacuum and is found tohave an index of refraction of 11 1.5261. The compound thereby formed isalpha-chloro-N-3-phenoxypropyl-N-2-methoxyethyl acetamide.

Example II The reaction vessel was charged with 20 g. of 20% sodiumhydroxide 100 ml. of chloroform and 15.9 g. of 3-phenoxypropyl ethylamine. 11.3 g. of chloroacetyl chloride were gradually introduced intothe reaction vessel at a controllable rate. After the reaction had beencompleted the product was separated by distillation at 0.45 ml. totalpressure and at a temperature of 158 160 C. The index of refraction n;;was 1.5325. The compound thereby formed isalpha-chloro-N-3-phenoxypropyl-N-ethyl acetamide.

Example III Using the procedure of Example I, except substitutingcyclohexyloxypropyl amine for the phenoxy propyl methoxyethyl amine theresulting product is identified as alpha-chloro-N-cyclohexyloxypropylacetamide.

Example IV The procedure of Examples I and II was repeated exceptN-(phenoxyethoxypropyl) amine was used in the reaction. The resultingproduct is alpha-chloro-N-phenoxyethoxypropyl acetamide.

Example V By methods analogous to the above all of the alphachloroacetamides with structures defined in the following table were prepared,all of which had remarkable herbicidal activity as demonstrated in thesame table.

Relative value of the claimed compounds was determined by plantinggreenhouse flats with seeds of numerous different plants eachrepresenting a principal botanical type as follows:

A Wild oat.

B Brome grass.

C Rye grass.

D Foxtail.

E Barnyard grass. F Crabgrass.

G Pigweed.

H Buckwheat.

I Mustard (radish). J Beet, sugar.

K Cotton.

L Corn.

M Field bindweed. N Morning glory (wild).

The following table of numerals will be used to designate the relativepre-emergence herbicidal effect of the various haloacetamides:

0 No phytotoxity. 1 Slight phytotoxity. 2 Moderate phytotoxity.

3 Severe phytotoxity.

e, such as talc, th, Fullers earth,

d calcium car- 0 98 percent by lied to plant or dilution d solidherbicidanger if they are f a disk-plow upon the physical TheN-substituted are only limitedly formulations will lids partietous earulfur; and the chemically such as the acid washed bentonite,

active ingredient.

The known water-insoluble substituted des may be water soluble and mererock phosphate and s of the entire formulation as app yllite, quartz,diatomac More concentrated he attapulgites; other minerals in naturalstat pyroph chalk,

modified minerals,

precipitated calcium phosphate, precipitate The liquid compositions forher bonate and colloidal silica. These diluents may represent 0 asubstantial portion, for example 50 t weig soil. by the user in order tothe most effective usage. 5 dal formulations can be used with less mixedwith the surface soil by means 0 or harrow at the time of application.

tions or other liquid dispersions. 0 medium will depend to some extentproperites of the alpha-haloacetami dissolution will then provi theN-substituted alpha-haloacetamides 5 soluble in water and thereforeaqueous necessarily be dispersions of minute drops or so cles of thewater-insoluble substance aqueous medium.

per acre as well for example from f this invention the fol-ABCDEFGHIJ'KLMNOPQRS RateABODEFGHIU'KLMNOPQRSAlpha-chloro-N-phen0xyethoxypropyl acetamide Alphachloro-N-phenoxypropylacetamide.

Alpha-chloro-N ,N-di(3-phenoxypropyl) acetamide.

lications of small for example 100 pounds per ses is more pro- Atheavier levels of appli- 50 pounds per acre, the selecd the generalherbicidal effects bicidal effects, application may f a growing plant.The re-emergence application formulations thereof on or subsequent tothe plantd method is to plant the with a formulation of the e the topsoil layer and her prior to or subsequent In order to demonstrate thecritical structure of the 25 he practice 0 he lack of herbicidalproperties for ds not included within the scope compounds used in tlowing table shows t homologous compoun of the claims.

Alpha-chloro-N ,N-diphenoxyethyl acetamide Alpha-chloro-N-phenoxypropyl-N-phenyl acetamide Valuable herbicidal effects, especially with respectto observed from app low as 0.1 pound The selective activity on grasnounced at lower levels of application, one to 15 pounds per acre.

To obtain the general her be made by spraying the foliage 0 selectiveactivity is observed by p by spraying the compound or her prior to ingof the seed. The preferre ound which will permeat by contact eitgrasses, will be amounts, often as as at higher concentrations,

acre.

cation, for example 10 to tivity is less pronounced an are obtained.

i the soil surface eit seed first and spray the surface comp destroy thegrasses to germination.

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c T. a m .w anew m f a m d 1 m .B O O 0 0 I e e .u S 0 g m V W m H e H m3H e scn M uao m o n a.w e.nP 8 f h S m d 0 to .1 ms w fpww &6 m rhynolp a H t H O C a n 1 3.1 d. h :1 S m de r cs h m m Phm W MW mwfiomhm 0 5 6 6 mJm d w m um ru nwm e o a .1 f m m h p 0 d t a t a em W e 1 dnf m a mi n m e e hm v me :mfi TC m cm s w a Ph mn We p 0 6 O f h avncdwc mm .W n umw in am? u nmm ro ma n m m n. tmdim us d 00 ron H gm newH H mm mu omi ace t bds m n i fih m dSc.wdP n unr f .m i g c b vmm a m aw vlcs 1 mmnmwm m mw e mdme m hmwm m m omwev u mfiama m diluents orextenders, dispersing agents to prevent local components of both solidand liquid types, and may be high concentrations, and a anionic,cationic or non-ionic types and includes convenin soil or soil waters.

tional soaps, such as the water-soluble salts of long chain carboxylicacids, the amino soaps such as the amine salts of long chain carboxylicacids, the sulfonated animal, etable and mineral oils, quaternary saltsof high ght acids, rosin soaps such as salts of abietic sulfuric acidsalts of high molecular weight organic which render the compositionsperm flowing. Thus hygroscopic material unless the compositions a toserve as an aid to the diluents, preferably pulverulent or granu to beeffective carriers for the active ingredient, are the compounds, alginsoaps, ethylene oxide condensated with natural clays, such as chinaclays, the bentonites and the 75 faty acids, alkyl phenols andmercaptans, and other simple and polymeric compositions having bothhydrophilic and hydrophobic functions so as to enable the mixing ofotherwise immiscible ingredients. Generally, the surface active agentswill be only a minor portion of the formulation as used, for exampleless than 10 percent and frequently as low as 0.05 percent. In general,concentrations of from 0.5 to 5 percent are found to be optimum.

Many of the formulations are benefited by the incorporation of organicsolvents for the active components, such as the water-immiscible organicalcohols, ketones and hydrocarbons, for example isopropanol, benzene,acetone, methylethyl ketone, kerosene, and chlorinated hydrocarbons. Theproportions of such organic liquid additives will depend upon thesolubility properties of the active ingredient and may require as littleas 1 percent or as much as 20 percent in order to provide a uniformlydistributed formulation which is capable of maintaining its distributedstate during storagfi, use and after application to the soil or plantsurfaces.

The concentrated formulations may be both liquid and solid and maycontain from 50 to 98% of the active component. In the case of thecompletely water soluble herbicides higher percentages or even 100% maybe used. However, in most cases a smaller amount of a surface activeagent is desirable so that dilution in the field may be facilitated.

A useful formulation of the herbicidal compositions may involve thesolid or liquid concentrate of the active ingredient to which has beenadded formulation aids or conditioning agents so that the concentratesmay be mixed with a suitable extender or diluent in the field at thetime of use. Obviously, for this purpose the dispersing agents will bepresent in larger concentrations so that upon dilution with water or asolid extender, compositions containing optimum proportions ofdispersing agents and active component, will be prepared. The solid orliquid formulations are preferably applied by mechanical equipmentinvolving spraying or spreading the formulation on soil or plantsurfaces being treated. For this purpose readily fiowable compositionsare required, either liquid or solid in physical state. Thus a criticalaspect of the invention is the fluent carrier without which the optimumherbicidal effects cannot be achieved.

Both the solid and the liquid formulations above described are useful inthe application of herbicides because they facilitate the uniformdistribution and aid in the destruction of undesirable plants bymaintaining the active ingredient in a form which enables the promptassimilation by the plant and the efiicient utilization of its weeddestroying properties. The described conditioning agents enable theproper use to achieve the desired herbicidal effects by an unskilledoperator without elaborate equipment.

In addition to the above described herbicide conditioning agentsadjuvants may be added, such as insecticides, fungicides, nematocidesand other herbicides. By the use of the subject compounds at the lowgrass specific levels of application, substantial benefits can beobtained by the addition thereto of a broad leaf specific herbicide, forexample, 2,4-dichlorophenoxyacetic acid and the corresponding esters,amine salts and alkali metal salts, trichlorobenzoio acid andderivatives thereof, such as trichlorobenzyl chloride andtrichloro-toulene. In this manner, formulations of efiicient andeffective use can be provided.

This application is a continuation-in-part of application, Serial No.726,602, filed April 7, 1958, by Angelo J. Speziale and Philip C. Hamm,now abandoned.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

l. The method of selectively inhibiting the germination of grass seedsin contact with soil and the pre-emergent growth thereof, whichcomprises treating the said soil with a herbicidal amount of a compoundof the structural formula wherein Z-Z is acyclic radial of the classconsisting of phenyl and cyclohexyl; wherein Y is an alkyl radical of upto four carbon atoms and t is an integar from zero to three; wherein mis an integer from zero to three; wherein X is a chalkogen of the classconsisting of oxygen and sulfur; whereinr is an integer from one tothree; wherein p is an integer from zero to one; wherein q is an integerfrom one to two; wherein the sum of m and I does not exceed five;wherein n is an integer from one to four, provided that when q is two,then n is at least three; wherein W is a halogen selected from the classconsisting of chlorine and bromine; and wherein R is selected from theclass consisting of hydrogen, allyl and alkyl having up to three carbonatoms.

2. The method of selectively inhibiting the germination of grass seedsin contact with soil and the pre-emergent growth thereof, whichcomprises treating the said soil with a herbicidal amount ofalpha-chloro-N-ethyl-N- phenoxypropyl acetamide.

3. The method of selectively inhibiting the germination of grass seedsin contact with soil and the pre-en1ergent growth thereof, whichcomprises treating the said soil with a herbicidal amount ofalph-chloro-N-phenylthiopropyl acetamide.

4. The method of selectively inhibiting the germination of grass seedsin contact with soil and the pre-emergent growth thereof, whichcomprises treating the said soil with a herbicidal amount ofalpha-chloro-N-cyclohexyloxypropyl acetamide.

5. The method of selectively inhibiting the germination of grass seedsin contact with soil and the pro-emergent growth thereof, whichcomprises treating the said soil with a herbicidal amount ofalpha-chloro-N-Ii-phenoxypropyl acetamide.

6. The method of selectively inhibiting the germination of grass seedsin contact with soil and the pre-emergent growth thereof, whichcomprises treating the said soil with a herbicidal amount ofalpha-chloro-N,N-di(3- phenoxypropyl) actamide.

AFC-CH W References Cited in the file of this patent UNITED STATESPATENTS Suter et al Oct. 2, 1956 Martin et al Dec. 11, 1956 Hamm et al.:Agr. and Food Chem, vol. 5, No. 1, January 1957, pages 3032.

1. THE METHOD OF SELECTIVELY INGIBITING THE GERMINATION OF GRASS SEEDSIN CONTACT WITH SOIL AND THE PRE-EMERGENT GROWTH THEREOF, WHICHCOMPRISES TRATING THE SAID SOIL WITH A HERBICIDAL AMOUNT OF A COMPOUNDOF THE STRUCTURAL FORMULA